Flexure-type symmetrical oscillator

ABSTRACT

A flexure-type symmetrical oscillator for an electric timepiece, having a U-shaped part with two flexible limbs connected at their free ends to two rigid arms which in turn have counterbalancing masses at their free ends and drive transducers at the location where they are connected to the flexible limbs, the dimensioning of the arms and limbs being such that the instantaneous center of rotation thereof is substantially coincident with the center of gravity during flexure, whereby the frequency of the oscillator is substantially independent of changes of position and orientation of the oscillator with respect to gravity, means being provided which permits adjustment of the frequency of the oscillations of such an oscillator, like the regulator assembly of a conventional watch with balance-wheel and balance-spring, in view of the adjustments of the running of the watch.

United States Patent [72] lnventors Rene Besson;

Remy Chopard, Neuchatel, Switzerland [21] Appl. No. 852,811 [22] Filed Aug. 25, 1969 [45] Patented May 25, 1971 [7 3] Assignee Ebauches SA. [32] Priority Aug. 30, 1968 [3 3] Switzerland [31] 13,112/68 [54] FLEXURE-TYPE SYMMETRICAL OSCILLATOR 2 Claims, 3 Drawing Figs.

[52] U.S. Cl 58/23, 310/25 [51] Int. Cl G04c 3/00 [50] Field of Search 310/25, 36, 58, 23, 23 (TF) [56] References Cited FOREIGN PATENTS 451,021 5/ 1968 Switzerland 58/23TF 744,5ll 10/1966 Canada 58/23D Primary ExaminerRichard B. Wilkinson Assistant Examiner -Edith C. Simmons Attorneys-Kenwood Ross and Chester E. Elavin ABSTRACT: A flexure-type symmetrical oscillator for an electric timepiece, having a U-shaped part with two flexible limbs connected at their free ends to two rigid arms which in turn have counterbalancing masses at their free ends and drive transducers at the location where they are connected to the flexible limbs, the dimensioning of the arms and limbs being such that the instantaneous center of rotation thereof is substantially coincident with the center of gravity during flexure, whereby the frequency of the oscillator is substantially independent of changes of position and orientation of the oscillator with respect to gravity, means being provided which permits adjustment of the frequency of the oscillations of such an oscillator, like the regulator assembly of a conventional watch with balance-wheel and balance-spring, in view of the adjustments of the running of the watch.

PATENTEU HAYZSIBYI 3579;975-

INVENTOR.

Pm BESSON Rcfm CHOPARD FLEXURE-TYPE SYMMETRICAL OSCILLATOR BRIEF SUMMARY OF THE INVENTION The present invention relates to a flexure-type symmetrical oscillator, particularly for an electric timepiece.

- The oscillator according to the invention comprises a U- shaped part having two flexible limbs adapted toparticipate in flexure in the fashion of a tuning fork, and two rigid arms serving as counterbalances for the flexible limbs during flexure, one such rigid arm being connected to each of the flexible limbs at or adjacent the free end of the latter, the arrangement being such that, for each of the two symmetrical parts of said oscillator, the instantaneous center of rotation thereof is substantially coincident with the center of gravity thereof during flexure, whereby the frequency of the oscillator is substantially independent of changes of position and orientation of such oscillator with respect to the field of gravity, at least one of the said two rigid arms carrying, situated in the neighborhood ofits free extremity, an inertia-block fitted'thereon so as to be able to occupy several angular positions around an axis which does not coincide with its center of gravity, the whole in such a way that displacing this inertia-block about the said axis produces variations of the kinetic moment of the oscillator, which modifies the frequency thereof.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view of a symmetrical oscillator of flexure type for a timepiece.

FIG. 2 is a plan view of a detail of FIG. 1, at scale, and

FIG. 3 is a sectional view along line IIIllI of FIG. 2.

DETAILED DESCRIPT ION an enlarged enlarged part 4a. Each enlarged part 4a carries a counterweight 5 constituted by a washer forced on a trunnion 6 forced in the part 4a.

One of the parts 40 carries, fixed thereon at 7, a pawl 8 actuating a ratchet counting-wheel 9 forming the first element of the driving gear-train of the hands of the timepiece.

Each trunnion 6 carries, frictionally fitted thereon and retained by a head 60 of the trunnion, a regulating inertiablock formed by a three branch star-shaped piece 10. One of the branches of each star-shaped piece 10 is provided with a notch 11 producing an asymmetry of the piece 10 such that the center of gravity of the inertia-block does not coincide with its geometrical axis.

The result of this arrangement lies in the fact that by turning the inertia-blocks on the trunnion 6, the axes of which are perpendicular to the plane of oscillation of the oscillator, the kinetic moment thereof is modified, which modifies the frequency of its oscillations.

One of the branches of each inertia-block 10 has an index 12 situated opposite a graduation 13 which is carried by the terminal part 4a of the corresponding rigid arm 4, in a manner so that the displacements of the inertia-blocks can be controlled in a precise manner. These displacements will preferably be carried out by means of a three-finger tool engaged between the branches of the inertia-blocks.

it is to be noted that, theoretically, the frequency of the oscillations should be the same for the two limbs of the oscillator, so that no energy-consuming reaction occurs on the support. However, in practice, the corrections of frequency realized by means of the inertia-blocks permit to adjust the running of the watch even when these corrections are extremely small, so that they do not produce, between the two limbs of the oscillator, even if they are applied thereon in an unequal manner, a difference of frequency which is perceptible. This greatly facilitates the adjusting operations; the oscillator may, if necessary, even comprise only a single inertiablock fitted on one of its rigid arms.

We claim:

1. In a flexutre-type symmetrical oscillator for an electric timepiece comprising: a U-shaped part including two flexible limbs adapted to flex in the fashion of atuning fork, two rigid arms serving as counterbalances for the flexible limbs, the rigid arms being connected to respective flexible limbs adjacent the free ends of the latter and projecting therefrom parallel to the limbs along the complete length thereof and beyond the closed end of the U-shpaed part to form arm and limb units in a symmetrical arrangement, each arm and limb unit having an instantaneous center of rotation during flexure and being dimensioned to define a center of gravity substantially coincident with the instantaneous center of rotation whereby the frequency of the oscillator is substantially independent of changes of position and orientation of the oscillator with respect to the field of gravity, at least one of the two rigid arms mounting in the area of its free extremity an inertiablock fitted for occupying a plurality of angular positions around an axis out of coincidence with its center of gravity, with displacement of the inertia-block about the axis producing variations of the kinetic moment of the oscillator for modifying the frequency thereof, the frequency-regulating inertiablock being constituted by a washer frictionally fitted on a trunnion carried by the rigid arm with the washer having a recess such that its center of gravity is situated outside of its axis.

2. The oscillator as claimed in claim 1, the washer being constituted by a three branch star-shaped member in one branch of which is provided the recess. 

1. In a flexutre-type symmetrical oscillator for an electric timepiece comprising: a U-shaped part including two flexible limbs adapted to flex in the fashion of a tuning fork, two rigid arms serving as counterbalances for the flexible limbs, the rigid arms being connected to respective flexible limbs adjacent the free ends of the latter and projecting therefrom parallel to the limbs along the complete length thereof and beyond the closed end of the U-shpaed part to form arm and limb units in a symmetrical arrangement, each arm and limb unit having an instantaneous center of rotation during flexure and being dimensioned to define a center of gravity substantially coincident with the instantaneous center of rotation whereby the frequency of the oscillator is substantially independent of changes of position and orientation of the oscillator with respect to the field of gravity, at least one of the two rigid arms mounting in the area of its free extremity an inertia-block fitted for occupying a plurality of angular positions around an axis out of coincidence with its center of gravity, with displacement of the inertiablock about the axis producing variations of the kinetic moment of the oscillator for modifying the frequency thereof, the frequency-regulating inertia-block being constituted by a washer frictionally fitted on a trunnion carried by the rigid arm with the washer having a recess such that its center of gravity is situated outside of its axis.
 2. The oscillator as claimed in claim 1, the washer being constituted by a three branch star-shaped member in one branch of which is provided the recess. 